Li Runxuan, Eliceiri Matthew H, Li Jingang, Korakis Vasileios, Yang Rundi, Rho Yoonsoo, Blankenship Brian W, Grigoropoulos Costas P
Laser Thermal Laboratory, Department of Mechanical Engineering, University of California, Berkeley, California 94720, United States.
Department of Mechanical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea.
J Phys Chem C Nanomater Interfaces. 2025 Jan 22;129(5):2460-2466. doi: 10.1021/acs.jpcc.4c07330. eCollection 2025 Feb 6.
The continuing developments in semiconductor device technologies have prompted the need for advanced nanoscale processing techniques. Laser chemical processing offers significant advantages, including spatial selectivity, high localization, minimal material damage, and fast operation. Pulsed laser-induced dissociation of gas species serves as an essential process step, contributing to doping, etching, and other chemical modifications of semiconductor materials. However, the mechanisms behind the laser-gas interactions and subsequent surface modifications remain elusive. Here, we demonstrate ultraviolet picosecond laser-induced atomic layer etching of silicon in a gaseous chlorine environment, achieving self-limited etching with a precision of 0.93 nm/cycle. Through optical emission spectroscopy, we elucidate the transition energy states of laser-excited products during chlorination. Complementing our experimental findings, we perform numerical modeling that reveals the complex spatiotemporal dynamics of chlorine species, encompassing their generation, recombination, diffusion, and transient surface reaction with the silicon substrate. Our study demonstrates optical diagnostics of laser-induced chlorination in atomic layer etching, which can provide valuable insights into ultrafine chemical nanostructuring of semiconductor materials.
半导体器件技术的持续发展促使人们需要先进的纳米级加工技术。激光化学加工具有显著优势，包括空间选择性、高定位性、最小的材料损伤和快速操作。脉冲激光诱导气体物种的解离是一个重要的工艺步骤，有助于半导体材料的掺杂、蚀刻和其他化学改性。然而，激光与气体相互作用以及随后表面改性的背后机制仍然难以捉摸。在这里，我们展示了在气态氯环境中用紫外皮秒激光对硅进行原子层蚀刻，实现了精度为0.93纳米/周期的自限制蚀刻。通过光发射光谱，我们阐明了氯化过程中激光激发产物的跃迁能态。作为我们实验结果的补充，我们进行了数值模拟，揭示了氯物种复杂的时空动力学，包括它们的产生、复合、扩散以及与硅衬底的瞬态表面反应。我们的研究展示了原子层蚀刻中激光诱导氯化的光学诊断方法，这可以为半导体材料的超细化学纳米结构提供有价值的见解。
